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排序方式: 共有145条查询结果,搜索用时 109 毫秒
1.
Synthesis and biological activity of an azido derivative of paclobutrazol, an inhibitor of gibberellin biosynthesis 总被引:1,自引:1,他引:0
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Hallahan DL Heasman AP Grossel MC Quigley R Hedden P Bowyer JR 《Plant physiology》1988,88(4):1425-1429
A photolabile azido derivative of the kaurene oxidase inhibitor 1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-l-yl) pentan-3-ol (paclobutrazol) has been synthesized for use as a photoaffinity labeling agent. The compound was tested as an inhibitor of the oxidation of ent-kaurene catalyzed by cell-free preparations from endosperm of Cucurbita maxima. The I50 of the azido derivative was 9.5 nanomolar, which compares well with that of paclobutrazol (6.3 nanomolar in our measurements). The azido compound bound to Cytochrome P-450 in microsomes from Cucurbita maxima, and induced a Type II spectral change, with an apparent binding constant of 0.24±0.04 micromolar. 相似文献
2.
Gibberellin (GA) biosynthesis in cell-free systems from Cucurbita maxima L. endosperm was reinvestigated using incubation conditions different from those employed in previous work. The metabolism of GA12 yielded GA13, GA43 and 12α-hydroxyGA43 as major products, GA4, GA37, GA39, GA46 and four unidentified compounds as minor products. The intermediates GA15, GA24 and GA25 accumulated at low protein concentrations. The structure of the previously uncharacterised 12α-hydroxyGA43 was inferred from its mass spectrum and by its formation from both GA39 and GA43. Gibberellin A39 and 12α-hydroxyGA43 were formed by a soluble 12α-hydroxylase that had not been detected before. Gibberellin A12-aldehyde was metabolised to essentially the same products as GA12 but with less efficiency. A new 13-hydroxylation pathway was found. Gibberellin A53, formed from GA12 by a microsomal oxidase, was converted by soluble 2-oxoglutarate-dependent oxidases to GA1 GA23, GA28, GA44, and putative 2β-hydroxyGA28. Minor products were GA19, GA20, GA38 and three unidentified GAs. Microsomal 13-hydroxylation (the formation of GA53) was suppressed by the cofactors for 2-oxoglutarate-dependent enzymes. Reinvestigation of the endogenous GAs confirmed the significance of the new metabolic products. In addition to the endogenous GAs reported by Blechschmidt et al. (1984, Phytochemistry 23, 553–558), GA1, GA8, GA25, GA28, GA36, GA48 and 12α-hydroxyGA43 were identified by full-scan capillary gas chromatography-mass spectrometry and Kovats retention indices. Thus both the 12α-hydroxylation and the 13-hydroxylation pathways found in the cell-free system operate also in vivo, giving rise to 12α-hydroxyGA43 and GA1 (or GA8), respectively, as their end products. Evidence for endogenous GA20 and GA24 was also obtained but it was less conclusive due to interference. 相似文献
3.
Three-week-old shoots of the spring oilseed rape cv. Petranova ( Brassica napus L. ssp. napus ) were found by combined gas chromatography-mass spectrometry to contain GA1 , GA8 , GA15 , GA17 , GA19 , GA20 , GA24 , GA29 , 3-epi-GA1 and a previously uncharacterised C19 dicarboxylic acid that is probably structurally related to GA24 . Shoots of the winter cultivar Belinda, harvested at the early flowering stage, contained the same GAs with the exception of the C19 dicarboxylic acid and, in addition, GA34 and GA51 were identified. All material contained higher levels of GA20 than of GA1 ; the ratio of GA1 to GA20 was highest in shoots containing the largest proportion of young immature tissues. Soil treatment of cv. Petranova seedlings with the growth retardant BAS 111¨W [1-phenoxy-5,5-dimethyl-3-(1,2,4-triazol-1-yl)-hexan-4-ol] caused 80% reduction in height 18 days after treatment and the levels of all GAs were 20% or less that of control plants. Foliar treatment at the same dosage reduced height by 50% and caused an 85% or greater reduction in the concentrations of the GA1 precursors GA20 , GA19 and GA44 . However, the levels of GA1 , GA8 and GA29 were affected to a much smaller extent. Foliar application of BAS 111¨W to cv. Belinda 1 month after sowing resulted in only a 20% height reduction at flowering, but no uniform decrease in the concentrations of endogenous GAs at this stage. 相似文献
4.
Isolation and expression of three gibberellin 20-oxidase cDNA clones from Arabidopsis. 总被引:25,自引:8,他引:17
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A L Phillips D A Ward S Uknes N E Appleford T Lange A K Huttly P Gaskin J E Graebe P Hedden 《Plant physiology》1995,108(3):1049-1057
5.
Genetic regulation of gibberellin deactivation in Pisum 总被引:2,自引:0,他引:2
John J. Ross James B. Reid Stephen M. Swain Omar Hasan rew T. Poole Peter Hedden Christine L. Willis 《The Plant journal : for cell and molecular biology》1995,7(3):513-523
The regulation of gibberellin (GA) deactivation was examined using the sin (slender) mutation in the garden pea (Pisum sativum L.). This mutation blocks the deactivation of GA20, the precursor of the bioactive GA1. Firstly, crosses were made to combine sin with the GA biosynthesis mutations na, lhi and le-3. The combination sin na produced a novel phenotype, with long (‘slender’) basal internodes and extremely short (‘nana’) upper internodes. In contrast, the double mutant sin lhi was phenotypically dwarf. The mutation sin causes an accumulation of GA20 in maturing seeds, and this was unaffected by na, since the na mutation is not expressed in seeds. In contrast, lhi seeds did not accumulate GA20, since lhi imposes an early block on GA biosynthesis. Secondly, the effects of sin on several steps in GA deactivation were investigated. In maturing seeds, the mutation sin blocks two steps in GA20 metabolism, namely, GA20 to GA29, and GA29 to GA29-catabolite. In the vegetative plant, on the other hand, sin blocked the step GA20 to GA29, but not GA29 to GA29-catabolite; the steps GA20 to GA81 and GA20 to GA1 were also not impaired in this mutant. It is clear that the effects of sin, like those of na, are strongly organ-specific. The presence of separate enzymes for the steps GA20 to GA29 and GA29 to GA29-catabolite was suggested by the observation that GA8 inhibited the latter step, but not the former, and by the inability of GA20 and GA29 to inhibit each other's metabolism. It is suggested that the Sin gene may be a regulatory gene controlling the expression of two structural genes involved in GA deactivation. 相似文献
6.
W. Rüdiger P. Hedden H.-P. Köst D.J. Chapman 《Biochemical and biophysical research communications》1977,74(3):1268-1272
A cell-free system is described which incorporates []-geranylgeranyl pyrophosphate, but not free []-geranylgeraniol, into chlorophyll ageranylgeraniol. The esterifying enzyme is found in the 75,000 g pellet of a homogenate from maize shoots whereas most of the phosphatase activity remains in the supernatant. The enzyme is different from chlorophyllase which has been discussed in the literature as the possible esterifying enzyme. 相似文献
7.
A new product obtained by incubation of [2-14C ]-mevalonic acid with a cell-free system from Cucurbita maxima endosperm was identified by GC-MS as ent-kaura-6,16-dien-19-oic acid. When this compound was reincubated with the microsomal fraction it was converted to 7β-hydroxykaurenolide and hence to 7β,12α-dihydroxykaurenolide. The dienoic acid was also obtained by incubation of ent-kaurene, ent1-kaurenol, ent-kaurenal and ent-kaurenoic acid, but not ent-7α-hydroxykaurenoic acid, with the microsomal fraction. Thus, in the C. maxima cell-free system, the kaurenolides are formed by a pathway which branches from the GA pathway at ent-kaurenoic acid and proceeds via the dienoic acid. 相似文献
8.
A microsomal preparation from mycelia of the gibberellin (GA)-producing fungus Gibberella fujikuroi catalyzed the first two steps in the conversion of the biosynthetic intermediate GA12-aldehyde to gibberellic acid (GA3). [14C]GA12-Aldehyde was converted to radiolabelled GA14, the major product, together with smaller amounts of non-hydroxylated GA12. The microsomal activities required reduced pyridine nucleotides and molecular oxygen. However, GA12 and GA14 synthesis differed markedly in the preferred electron source. Formation of GA12 required NADH or NADPH, while GA14 synthesis from GA12-aldehyde occurred only with NADPH. Marked differences were also found in the activating effect of FAD. When NADPH was the reductant, the rate of GA14 synthesis was enhanced 3.5 times by 5 microM FAD while this flavin nucleotide did not alter the synthesis of GA12. In contrast, GA12 synthesis was activated 3.8 times by 50 microM FAD in the presence of NADH. Both activities were inhibited by carbon monoxide and cytochrome c. These properties suggest that the 3beta-hydroxylation of GA12-aldehyde and further oxidation of carbon 7 are catalyzed by cytochrome P-450 monooxygenases in Gibberella fujikuroi. 相似文献
9.
Modification of gibberellin production and plant development in Arabidopsis by sense and antisense expression of gibberellin 20-oxidase genes 总被引:10,自引:0,他引:10
Coles JP Phillips AL Croker SJ García-Lepe R Lewis MJ Hedden P 《The Plant journal : for cell and molecular biology》1999,17(5):547-556
Gibberellin (GA) 20-oxidase catalyses consecutive steps late in GA biosynthesis in plants. In Arabidopsis, the enzyme is encoded by a gene family of at least three members (AtGA20ox1, AtGA20ox2 and AtGA20ox3) with differential patterns of expression. The genes are regulated by feedback from bioactive GAs, suggesting that the enzymes may be involved in regulating GA biosynthesis. To investigate this, we produced transgenic Arabidopsis expressing sense or antisense copies of each of the GA 20-oxidase cDNAs. Over-expression of any of the cDNAs gave rise to seedlings with elongated hypocotyls; the plants flowered earlier than controls in both long and short days and were 25% taller at maturity. GA analysis of the vegetative rosettes showed a two- to threefold increase in the level of GA4, indicating that GA 20-oxidase normally limits bioactive GA levels. Plants expressing antisense copies of AtGA20ox1 had short hypocotyls and reduced rates of stem elongation. This was reflected in reduced levels of GA4 in both rosettes and shoot tips. In short days, flowering was delayed and the reduction in the rate of stem elongation was greater. Antisense expression of AtGA20ox2 had no apparent effects in long days, but stem growth in one transgenic line grown in short days was reduced by 20%. Expression of antisense copies of AtGA20ox3 had no visible effect, except for one transgenic line that had short hypocotyls. These results demonstrate that GA levels and, hence, plant growth and development can be modified by manipulation of GA 20-oxidase expression in transgenic plants. 相似文献
10.
Tudzynski B Hedden P Carrera E Gaskin P 《Applied and environmental microbiology》2001,67(8):3514-3522
At least five genes of the gibberellin (GA) biosynthesis pathway are clustered on chromosome 4 of Gibberella fujikuroi; these genes encode the bifunctional ent-copalyl diphosphate synthase/ent-kaurene synthase, a GA-specific geranylgeranyl diphosphate synthase, and three cytochrome P450 monooxygenases. We now describe a fourth cytochrome P450 monooxygenase gene (P450-4). Gas chromatography-mass spectrometry analysis of extracts of mycelia and culture fluid of a P450-4 knockout mutant identified ent-kaurene as the only intermediate of the GA pathway. Incubations with radiolabeled precursors showed that the metabolism of ent-kaurene, ent-kaurenol, and ent-kaurenal was blocked in the transformants, whereas ent-kaurenoic acid was metabolized efficiently to GA(4). The GA-deficient mutant strain SG139, which lacks the 30-kb GA biosynthesis gene cluster, converted ent-kaurene to ent-kaurenoic acid after transformation with P450-4. The B1-41a mutant, described as blocked between ent-kaurenal and ent-kaurenoic acid, was fully complemented by P450-4. There is a single nucleotide difference between the sequence of the B1-41a and wild-type P450-4 alleles at the 3' consensus sequence of intron 2 in the mutant, resulting in reduced levels of active protein due to a splicing defect in the mutant. These data suggest that P450-4 encodes a multifunctional ent-kaurene oxidase catalyzing all three oxidation steps between ent-kaurene and ent-kaurenoic acid. 相似文献